package com.zheng.study.base.bean.search.projection;

/**
 * 查询 - 参数 - Projection 帮助类
 * ============================================================================
 * author : fallenpanda
 * createDate:  2018/6/11 。
 * ============================================================================
 */
public class ProjectionHelp {

	/**
	 * 无
	 */
	public static Projection none(){
		return ProjectionNone.none();
	}

	/**
	 * 行数
	 */
	public static Projection rowCount(){
		return ProjectionRowCount.rowCount();
	}

	/**
	 * 行数
	 */
	public static Projection count(String field){
		return ProjectionCount.count(field);
	}

	/**
	 * 行数
	 */
	public static Projection countDistinct(String field){
		return ProjectionCount.countDistinct(field);
	}

	/**
	 * 最大值
	 */
	public static Projection max(String field){
		return ProjectionAggregate.max(field);
	}

	/**
	 * 最小值
	 */
	public static Projection min(String field) {
		return ProjectionAggregate.min(field);
	}

	/**
	 * 平均值
	 */
	public static Projection avg(String field) {
		return ProjectionAggregate.avg(field);
	}

	/**
	 * 和
	 */
	public static Projection sum(String field) {
		return ProjectionAggregate.sum(field);
	}

}
